A 6 week course of azithromycin treatment has no beneficial effect on atherosclerotic lesion development in apolipoprotein E-deficient mice chronically infected with Chlamydia pneumoniae

Objectives: To evaluate whether antimicrobial chemotherapy prevents acceleration of atherosclerotic lesion development induced by infection with Chlamydia pneumoniae. Methods: ApoE-deficient mice which develop hyperlipidaemia and atherosclerosis spontaneously were inoculated intranasally with C. pneumoniae. Animals were treated with azithromycin for 6 weeks after the third inoculation and the atherosclerotic lesion areas in the aortic sinus were measured by computer-assisted morphometry. Results: At 12 weeks post-infection, infected untreated animals developed significantly larger lesion areas compared with sham-inoculated controls (8.7 x 10(4) +/- 2.3 x 10(4) mu m(2) versus 5.6 x 10(4) +/- 2.4 x 10(4) mu m(2)). However, there were no differences in lesion size of infected mice treated with azithromycin in comparison with untreated infected controls (11.0 x 10(4) +/- 3.0 x 10(4) mu m(2) versus 8.7 x 10(4) +/- 2.3 x 10(4) mu m(2)). Conclusions: Antibiotic treatment against C. pneumoniae has no beneficial effects on hyperlipidaemia-induced atherosclerosis accelerated by C. pneumoniae in a mouse model.